Using qemu and Docker for hardware emulation on Github Actions

ci.yml

jobs:
  s390x: # run https://hub.docker.com/r/s390x/ubuntu under qemu
    name: "s390x bigendian"
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: |
          docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
          docker run --rm -v $PWD:/work -w /work \
            --platform linux/s390x s390x/ubuntu:oracular \
            sh -c "
              apt update &&
              apt install -y build-essential ruby-dev ruby-bundler libyaml-dev pkg-config &&
              bundle install &&
              bundle exec rake compile test
            "